The error says this
Arduino: 1.8.17 Hourly Build 2021/09/06 02:33 (Windows 10), Board: "Arduino Uno"
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h: In function 'int sensor_ph()':
sensor.h:77:44: error: lvalue required as left operand of assignment
Po = 7.00 + ((PH7 - TeganganPh) / PH_step);
^
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h: At global scope:
sensor.h:4:7: error: redefinition of 'float PH_step'
float PH_step;
^~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:4:7: note: 'float PH_step' previously declared here
float PH_step;
^~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:5:5: error: redefinition of 'int nilai_analog_PH'
int nilai_analog_PH;
^~~~~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:5:5: note: 'int nilai_analog_PH' previously declared here
int nilai_analog_PH;
^~~~~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:6:8: error: redefinition of 'double TeganganPh'
double TeganganPh;
^~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:6:8: note: 'double TeganganPh' previously declared here
double TeganganPh;
^~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:9:7: error: redefinition of 'float PH4'
float PH4 = 3.15;
^~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:9:7: note: 'float PH4' previously defined here
float PH4 = 3.15;
^~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:10:7: error: redefinition of 'float PH7'
float PH7 = 2.5;
^~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:10:7: note: 'float PH7' previously defined here
float PH7 = 2.5;
^~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:17:24: error: redefinition of 'int analogBuffer [30]'
int analogBuffer[SCOUNT];
^
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:17:5: note: 'int analogBuffer [30]' previously declared here
int analogBuffer[SCOUNT];
^~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:18:28: error: redefinition of 'int analogBufferTemp [30]'
int analogBufferTemp[SCOUNT];
^
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:18:5: note: 'int analogBufferTemp [30]' previously declared here
int analogBufferTemp[SCOUNT];
^~~~~~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:19:5: error: redefinition of 'int analogBufferIndex'
int analogBufferIndex = 0, copyIndex = 0;
^~~~~~~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:19:5: note: 'int analogBufferIndex' previously defined here
int analogBufferIndex = 0, copyIndex = 0;
^~~~~~~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:19:28: error: redefinition of 'int copyIndex'
int analogBufferIndex = 0, copyIndex = 0;
^~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:19:28: note: 'int copyIndex' previously defined here
int analogBufferIndex = 0, copyIndex = 0;
^~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:20:7: error: redefinition of 'float averageVoltage'
float averageVoltage = 0, tdsValue = 0, temperature = 25;
^~~~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:20:7: note: 'float averageVoltage' previously defined here
float averageVoltage = 0, tdsValue = 0, temperature = 25;
^~~~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:20:27: error: redefinition of 'float tdsValue'
float averageVoltage = 0, tdsValue = 0, temperature = 25;
^~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:20:27: note: 'float tdsValue' previously defined here
float averageVoltage = 0, tdsValue = 0, temperature = 25;
^~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:20:41: error: redefinition of 'float temperature'
float averageVoltage = 0, tdsValue = 0, temperature = 25;
^~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:20:41: note: 'float temperature' previously defined here
float averageVoltage = 0, tdsValue = 0, temperature = 25;
^~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h: In function 'int getMedianNum(int*, int)':
sensor.h:23:5: error: redefinition of 'int getMedianNum(int*, int)'
int getMedianNum(int bArray[], int iFilterLen)
^~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:23:5: note: 'int getMedianNum(int*, int)' previously defined here
int getMedianNum(int bArray[], int iFilterLen)
^~~~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h: In function 'int sensor_tds()':
sensor.h:48:5: error: redefinition of 'int sensor_tds()'
int sensor_tds() {
^~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:48:5: note: 'int sensor_tds()' previously defined here
int sensor_tds() {
^~~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h: In function 'int sensor_ph()':
sensor.h:72:5: error: redefinition of 'int sensor_ph()'
int sensor_ph() {
^~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:4:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\sensor.h:72:5: note: 'int sensor_ph()' previously defined here
int sensor_ph() {
^~~~~~~~~
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h:1:0,
from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:
sensor.h:77:44: error: lvalue required as left operand of assignment
Po = 7.00 + ((PH7 - TeganganPh) / PH_step);
^
In file included from C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\Tes_sensors_dif_tab.ino:7:0:
C:\Users\Ghoond\Documents\Arduino\Tes_sensors_dif_tab\menu.h: At global scope:
menu.h:4:12: error: expected constructor, destructor, or type conversion before ';' token
sensor_ph();
^
menu.h:5:13: error: expected constructor, destructor, or type conversion before ';' token
sensor_tds();
^
exit status 1
lvalue required as left operand of assignment
but on the arduino IDE line
Po = 7.00 + ((PH7 - TeganganPh) / PH_step);
on function sensor_ph() are blocked red